Mammalian keratinous tissue, particularly human skin, is subjected to a variety of insults by both extrinsic and intrinsic factors. Such extrinsic factors include ultraviolet radiation, environmental pollution, wind, heat, infrared radiation, low humidity, harsh surfactants, abrasives, etc. Intrinsic factors, on the other hand, include chronological aging and other biochemical changes from within the skin. Whether extrinsic or intrinsic, these factors result in visible signs of skin damage. Typical skin damage in aging or damaged skin include fine lines, wrinkling, hyperpigmentation, sallowness, sagging, dark under-eye circles, puffy eyes, enlarged pores, diminished rate of turnover, and abnormal desquamation or exfoliation. Additional damage incurred as a result of both external and internal factors includes visible dead skin i.e., flaking, scaling, dryness, and roughness.
Currently, there are a number of personal care products that are available to consumers, which are directed toward improving the health and physical appearance of keratinous tissues such as the skin, hair, and nails. The majority of these products are directed to delaying, minimizing or even eliminating skin wrinkling, spots, and other histological changes typically associated with the aging of skin or environmental damage to human skin. Consumers prefer topically applied products since they are not only effective, but also safe and pleasant to use.
An N-acyl amino acid, particularly N-acyl derivatives of phenylalanine or tyrosine, their isomers, or their salts are known for being useful in preventing or treating various ketatinization disorders. These compounds are cosmetic active agents of choice such as for whitening products.
However, it has been observed that these compounds are difficult to dissolve in cosmetic compositions, and these active agents have a tendency to recrystallize. Oil compounds such as Eldew SL-205 from Ajinomoto, and octyldodecanol are known as an solvent for N-acyl amino acid compounds.
Based on the foregoing, there is a continuing need to formulate cosmetic compositions containing an N-acyl amino acid compound that can provide stable delivery of skin actives.